Yielding contact unit



Oct. l0, 1939. F. H. COLE YIELDING CONTACT UNIT Filed June 28, 1957 il. I

Patented Oct. l0, 1939 UNITED STATES PATENT OFFICE YIELDrNG CONTACT UNIT Application June 28, 1937, Serial No. 150,662

3 Claims.

My invention relates toelectrical devices, more particularly circuit breakers, and is directed to an improved form of replaceable contact unit for a circuit breaker and the like.

6 In a circuit breaker for large currents and high potentials, it is highly essential that the circuit-controlling contacts close together in a positive manner with absolutely no bounce to avoid a destructivewelding action. It is also lll essential, when a pluralityof contacts are carried by one operating member, to insure that the abutment ofA one pair of contacts together will not prevent proper abutment of the remaining contacts associated with the'operating member. For both .of 'these reasons a` yielding mounting is desirable for atleast one contact in each cooperating pair of contacts, such yielding `mount-V ing being commonly provided by a relatively heavy spring means.

In the manufacture or repair of such mecha-- nism, two adjustments are involved, the spacial adjustment of the two contacts of a pair, and

lthe pressural adjustment of the pair, the first adjustment determining vthe point in the clos- 25- ing movement of the circuit breaker at which the complementary contacts meet, and the second adjustment determining the pressure developed between the contacts in the lclosing Y movement beyond that point. It is generally' 30. found convenient to associate one of these adjustments with one contact of a pair and the other adjustment with the other contact, bothV for simplicity in manufacture and to keep one adjustment means from `interfering with the 35 other. A feature of my invention is that it provides for associating both of these adjustments with the same contact, which contact may be either the stationary or the movable contact of a pair of contacts.

One object of my invention is to simplify the manufacture and repair of a circuit breaker by providing a bench-assembled self-contained Acontact unit for detachable installation in a circuit breaker with minimum adjustment re- 45 quired. v

Another object is to provide such a unit in which the yielding feature is pre-adjusted, not requiring adjustment or manipulation in the assembly of the unit to the circuit breaker.

Another object of my invention is to provide both the yielding feature and the means for spacial adjustment in the same contact, without conict with each other. In Vthe preferred form of my invention I propose to achieve this object ll by, in eifect, mounting the yielding means on (Cl. 200e-166) the spacial adjustment to be moved bodily thereby without affecting the character of the yielding action.

The conductors of a circuit breaker, particularly in the vicinity of the open contacts, should 6 be smooth and free from projections, whereas adjustment means generally involves irregular configurations. Further irregularity of contour arises from thenecesslty, usually, of providing a exible but direct connecting means between a 0 movable contact and its associated conductor, especially when the contact is spring-mounted for movement relative to the conductor. One object of myinvention is to provide a contact unit in which all such undesirably irregular l members are eiectively shielded.

With reference to the yielding feature itself, I have the objects of providing a simple means of pressure regulation in the manufacture of the unit, and of achieving the advantages of a relatively long spring acting between the contact and its associated conductor withoutV providing acorresponding distance between the contact and conductor.

The above and other features and advantages of my invention will be apparent in the detailed description to follow:

.Broadly described,.my invention comprises a bodyV adapted for releasable and adjustable at-y tachment to a conductor in combination with a contact element yieldably e tending from said body,

In the drawing, which -is to be illustrative only,

Fig. 1 is a fragmentary sectional view of a 35 circuit breaker showing structure associated with considered as two cooperating contacts, the parts being shown the device;

in the open position of l Fig. 1 with the parts in Fig. 2 is similar to closed circuit position;

Fig. 3 is a cross-section taken as indicated by the line 3--3 of Fig. 2; and

Fig. 4 is a section taken asindicated line 4-4 of Fig. 1.

For the purpose of exemplifying the principles 45 involved, I shall describe my invention as specically adapted to a circuit breaker employing an oil dielectric, more particularly a vcircuit breaker of the type disclosed in my copending application Serial No. 146,786, illed June '7, 1937, 50 patented May 2, 1939, Number 2,156,450, entitled Method' of and apparatus for interrupting an electric circuit; but it will be understood that the principles of my invention are also applicable Ato other types of switching devices.

by the The drawing shows an arc quenching member I0 movable with respect to a plurality of relatively iixed contact elements il, the arc quencher having a plurality of contact elements AI2 forming pairs with the contact elements II, only one of the pairs being shown in the drawing. The contact elements I2 are interconnected by a suitable conducting member I3 to which the contact elements may be secured by screw-threaded engagement, as shown. Each of the contact elements 2 is xed at the inner end of a passage I4 of the arc quenching member that is adapted to receive the corresponding contact element II. In the open circuit position of the parts, the arc quenching member I0 lsin spaced relation to the Contact element Il, as is shown in Fig. 1, and in the closed circuit position of the parts the arc quenching member is moved sufliciently toward the contact element I to provide pressural engagement of the two contacts at the inner end of the passage H, as shown in Fig. 2.

In the construction chosen for illustration, the contact element Il is associated with an electrical conductor I5 that extends downward through a porcelain tube I8 and terminates in a permanent end-member generally designated I9, the end-member being adapted for the purposes of my invention.

I propose to provide as a part of my unit a body releasably attachable to the end-member I9 and adapted to form therewith a chamber or shielded space 20 for housing various irregular portions of the unit, whereby the exterior of the unit may present a smooth surface effective for equalization of electrostatic stress distribution. For such purpose I may shape the end-member I9 to present an inverted cup having an internally threaded cylindrical portion 2| and an end wall 22 having a suitable vent aperture 23. 'Ihe body, generally designated 25, is also cup-shaped and has a cylindrical wall 26 with exterior threads for engagement with the cylindrical wall 2| of the end-member I9 whereby the body 25 may be adjusted axially with respect to the end member I9. For the purpose of fixing the body at an adjusted position, a suitable lock-nut 21 may be prvided. Preferably, the bottom of the body will comprise a separable member in the form of a bushing 28.

Integral with the cylindrical wall 26 and extending inwardly therefrom are a lug n at an upper level and a nger 3| at a lower level, the

nger terminating in a downwardly extending tubular end 32. In the preferred form of my invention, the contact element -is a hollow member preferably tubular in configuration, the tubular member slidingly embracing at its inner end the cylindrical portion 32 of the finger 3| and being in turn slidingly embraced by the bushing 28. It will be .apparent that the portion 32 of the finger and the bushing serve as cooperating guides to keep the contact element II in proper alignment. f

Some provision is required-for limiting the outward movement of the contact element with respect to the body 25. For this purpose a collar 33 may be -iixed on the contact element I |A near the inner end thereofl at a position permitting* a. substantial range of movement of the contact between a position with the collar abutting the bushing v28 and a position with the inner end of the contact stopped by the iinger 3|. 'Preferably, this range of movement will be sufiicient yto accommodate not only the yielding action dccaracas sired, but also an additional substantial tolerance to avoid the necessity of close-adjustment.

In' the preferred form of my invention the yielding means ior urging the contact element toward its extended position comprises a helical expansible spring 35 within the contact element in compression between the outer end wall 35 of the Contact element and the face 3T of the iinger end 32. It is to be noted as a feature of my invention that a relatively long spring for acting between the body of the unit and the contact element is accommodated by the Aspace within the contact element, the virtue of such an arrangement being that I incorporate in the operation of my device the desirable characteristics of a relatively long springwithout ailecting' the compactness of my unit. In one embodiment of my invention, for example, I arrange for a minimum compression of twenty pounds on the part of the spring 35 in the open position of the circuit breaker and I select a spring of such character that additional compression of approximately three-eighths of an inch caused by closing the circuit increases the pressure of the spring to approximately nity pounds. Also, I provide an additional permissible movement of three-eighths of an inch on the part of theA contact element II for tolerance of adjustment.

In the bench assembly of the contact unit, variations in the characteristics of individualI springs may be offset by means in the form of discs 38 adapted to be placed in the closed end of the contact element as spacer means for increasing the compression of the spring 35. Such spacer means may also be employed for the purpose of increasing the pressure of the springs to meet the requirements of particular installations.

For direct electrical connection between the unit body 25 and the contact element II, I provide a pair of flexible conductors, such as laminated conductors 39 andvlll. The conductor 39 has'its lower end Iixedly seated in a transverse groove 4| of the collar 33 and its upper end engaged by a suitable screw I2 in the finger 3|. In a similar manner the contact Il) has its lower end seated in a second transverse groove 43 in the collar 33 and has its upper end engaged by asuitable screw M in the lug 3l.

I have provided in the manner described a replaceable contact unit that may be installed by simply threading it to the complementary endmember of the circuit breaker, special adjustment being provided by the threaded engagement and xed by the cooperating lock-nut. The yielding characteristic of the contact unit is ilxed at the time of manufacture, both with respect to the amount of yielding movement andthe pressure resisting such movement, so that such matters do not require the time and attention of the person who installs the contact unit. The result is not only a saving of time inthe installation of the unit, but also a uniformity of contact adjustment.

-It will be apparent from my disclosure that changes and modifications of the specific form set forth may be made without departing from the principles involved, and it is to be understood that I reserve the light to all such changes and modifications that properly come within the scope Voi? my appended claims.

v tially rigid adjustable attachment to vvsaid ,con-

doctor; said body forming with said conductora 76 portion of said contact element being wholly sursubstantially smooth outer surface for shielding purposes; means to lock the connection between the body and conductor at a selected adjustment; a contact element lretractably extending from the body; yielding means acting between the contact element and the interior of said body to urge said contact element toward its extended position through an end wall of said body; and con. ductor means Within said body flexibly interconnecting said body and contact element. n

2. A contact'unit for a high voltage circuit breaker having a lead-in conductor terminating in contact adapter structure, comprising a hollow shielding body of conducting material mounted on said adapter structure, said shielding bodyv being rigidly attached to said adapter and bodily adjustable along the longitudinal axis thereof, a relatively movable contact element slidably mounted in an end wall of said shield and biased outwardly therefrom, means for adjusting the bias on'said contact element and a ilexible conductor interconnecting said shield and contact element, said flexible conductor and the reentrant rounded by said thereof.

3. A contact unit for a high voltage circuit breaker having a lead-in conductor terminating shield in the operative position in a contact adapter, said adapter having a depending annular ange, comprising a cup-like shield of conducting material adapted to be rigidly connected in substantially flush-surface relation to said flange, means for adjusting said shield with respect to the longitudinal axis of said adapter, a contact element mounted in said shield and extending through` the end thereof opposite said adapter, means for resiliently biasing said contact element towards the extended position, said contact element and resilient means being wholly mounted within said shield, and a flexible conductor electrically connecting said shield and element whereby the aforesaid contact and shielding structure can be detached as a unit with respect to said adapter.

FRED H. COLE. 

